CVE-2026-68421
Received Received - Intake

Kernel Scheduling Race Condition in Linux

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Don't warn on core-sched forced idle in put_prev_task_scx() put_prev_task_scx() warns when a runnable task drops to a lower sched_class without SCX_OPS_ENQ_LAST, on the assumption that balance_one() would have kept it running. Core scheduling breaks that: a forced-idle SMT sibling reschedules through the core_pick fast path in pick_next_task(), which skips pick_task_scx() and thus balance_one(), so a runnable task can drop to idle with ENQ_LAST unset. Gate the warning on sched_cpu_cookie_match(): a cookie mismatch means core scheduling forced the idle, while a match (or core scheduling off) still catches a genuine missing-ENQ_LAST drop.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
CVE-2026-68421
EUVD
EUVD-2026-55607

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This is a Linux kernel vulnerability where a warning in the scheduler could incorrectly trigger when core scheduling forces a CPU into idle state. The issue occurs in the put_prev_task_scx function, which assumes a runnable task should remain running unless properly enqueued. Core scheduling bypasses normal balancing checks, causing false warnings about task scheduling.

Detection Guidance

This vulnerability is specific to the Linux kernel's sched_ext subsystem and may not have direct network detection methods. Monitor kernel logs for warnings related to put_prev_task_scx() or core scheduling forced idle events. Check for unusual task scheduling behavior or performance anomalies in SMT-enabled systems.

Impact Analysis

This vulnerability primarily affects system stability and performance by generating unnecessary warnings in kernel logs. It does not directly enable security exploits but may obscure real issues during debugging. Systems using core scheduling features could experience increased log noise.

Mitigation Strategies

Apply the latest Linux kernel patches that address this issue. Disable core scheduling if not required by setting the kernel parameter core_sched=0. Monitor system logs for related warnings and update sched_ext components if used.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-68421. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart